1. Field of the Invention
The invention relates to an apparatus for the internal inspection of pipes and tubes or the like, comprising an ultrasonic measuring head and a cable coupled to the measuring head, which cable can be coupled outside the pipe or tube to be measured to a device processing the measuring data. Such an apparatus is used for the internal inspection of pipes and tubes of in particular industrial furnaces in the petrochemical and chemical industry or in other (heavy) industries. The inspection serves for the detection of internal and surface corrosion such as pitting, but also for the detection of a reduction in wall thickness, mechanical deformations such as dents, and ovalities resulting from local overheating. In addition, the apparatus can be used to determine to what extent the pipes and tubes are fouled. To perform the measurement with the apparatus according to the preamble of claim 1, it is advantageous to use a measuring head as patented and specified in applicant's Dutch patent 1006007.
2. Description of Related Art
One of the problems that manifests itself when inspecting industrial furnaces of the above kind, is that they are constructed from a large number of horizontal or vertical pipes that are coupled by means of so-called return bends. These return bends have a radius of 1D, that is to say a bend diameter that is equal to the internal diameter of the pipe, and a gradient of 180°. As a result, every known apparatus for the internal inspection of such pipes and tubes will become lodged after two and at the most after three bends. A foremost problem is, however, that there is no known system of dimensions that allow the passage through bends having a radius of 1D.